The overall objectives for the proposed research can be outlined as follows: To clarify further the regulatory mechanisms of the numan natural killer cells. To develop methods to identify the cellular components of these regulatory pathways and study their interelationships in various disease states in order to learn about the significance of the NK system in the etiology and control of such diseases. To study the mechanism of killing mediated by the NK cells. To perform comparative studies in various animal species on the role of the large granular lymphocyte (LGL) shown to be the mediator of NK activity in man. To characterize further the antigenic profile on normal and neoplastic glial cells. To develop specific monoclonal reagents against well characterized antigenic components on human normal and neoplastic glial cells for experimental and clinical diagnostic work.